This invention relates generally to multiple nozzle injection molding apparatus and more particularly to such apparatus wherein each nozzle is screwed into a socket in a mounting base secured in place adjacent a melt distribution manifold.
Injection molding apparatus having a number of heated nozzles extending from a heated melt distribution manifold into a cooled mold are well known. U.S. Pat. No. 5,282,735 to Gellert which issued Feb. 1, 1994 shows the rear end of the heated nozzles being attached to the melt distribution manifold by being screwed into it. However, it is usually necessary to locate both the front and rear ends of the heated nozzle in the mold to allow the melt distribution manifold to move slightly laterally relative to the rear end of the nozzles to allow for heat expansion and contraction of the melt distribution manifold. This is usually done by securing a rear collar portion of the nozzle to the melt distribution manifold with screws which allow sufficient lateral movement to provide for thermal expansion and contraction. As shown, for instance in U.S. Pat. No. 4,768,283 to Gellert which issued Sep. 6, 1988, the collar portion is usually an integral part of the heated nozzle. However, as seen in U.S. Pat. No. 5,507,635 to Gellert which issued Apr. 16, 1996, the collar portion can be separable from the rest of the heated nozzle. In U.S. Pat. No. 5,268,184 to Gellert which issued Dec. 7, 1993, the nozzle has separate front and rear parts. Another variation of a removable collar portion having two segments held together by a retaining ring is shown in U.S. Pat. No. 5,429,491 to Gellert which issued Jul. 4, 1995. However, all of these previous configurations have the disadvantage that in order to remove one of the thermocouple or one of the nozzles for cleaning or replacement, it is necessary to first remove the mold from the molding machine and the manifold and cavity plates from the rear back plate.